Characterization of traditional dyes of the Mediterranean area by non-invasive UV-Vis-NIR reflectance spectroscopy

An understanding of the composition of natural and synthetic dyes used in ancient textiles and rugs is important for conservation purposes and to determine the origin of a textile or rug. Colorants or dyes are traditionally analysed by means of separation methods and ultraviolet-visible spectroscopic techniques that require sampling. This contribution focuses on establishing a fast, non-invasive, and in situ measurement procedure based on ultraviolet-visible-near infrared reflectance spectroscopic techniques for the characterization of dyes in ancient textiles or rugs manufactured in the Mediterranean basin and Middle East. For this purpose a collection of specimens on wool supports was prepared following ancient dyeing recipes. The samples were subsequently measured in the 230-2500 and 350-1700 nm ranges to create a spectroscopic database that was then compared with spectra acquired from textiles and rugs in order to characterize the dyes present.